problem in boost circuit

[hemnath]

I have the output from Mosfet Source pin as +3V. I'm trying to boost this +3V to +5V using LM2623. But the problem is,
when i connect mosfet of Source to input to LM2623. Voltage at source pin (which is +3V) drops to 0.7V and at the output of the LM2623 is 1.1V.
Then, i have disconnected the mosfet source pin and LM2623.
I have applied external voltage from a voltage source to +3V to input of LM2623. In this case, output from the LM2623 is +5V, looks good.

What could be the problem? I think it may be due to higher impedance? If it's, how to make it to higher impedance to lower impedance.

Please help!!!

 

[pwdixon]

You can't get something for nothing, this is a power transfer mechanism, low volts/high current capability in high volts/lower current capability out, I think of it as a power transformer of sorts so if your input can't deliver the current the output cannot be produced that's all there is to it.

 

[FvM]

A MOSFET source pin as such doesn't source electrical power. We have to discuss a circuit to clarify the problem.